Acid radio stations play music with roots in the early house music scene of Chicago. The sound of Acid music (or Acid House) is stongly associated with the squelching/tweaking sound of Roland TB-303 bassline monosynth/step sequencer. The sound has since found its way into many other genres, notably being a shaping influence in what would later become known as Trance. Acid internet radio stations feature artists such as Phuture and 808 State.